set null -> rm sync backtrace

Starting program: /usr/bin/python gst_set_null_rm_sync.py
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff2794700 (LWP 10411)]
[New Thread 0x7ffff1f93700 (LWP 10412)]
[Thread 0x7ffff1f93700 (LWP 10412) exited]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff2794700 (LWP 10411)]
0x00000000004c6fc0 in tupleconcat.24236 ()
(gdb) thread apply all backtrace

Thread 2 (Thread 0x7ffff2794700 (LWP 10411)):
#0  0x00000000004c6fc0 in tupleconcat.24236 ()
#1  0x00007ffff43f5d10 in bus_sync_handler (bus=<optimized out>, message=<optimized out>,
    user_data=0x9cad40) at gstbus.override:59
#2  0x00007ffff3870fac in gst_bus_post (bus=0xd13480, message=0xc25580) at gstbus.c:322
#3  0x00007ffff387ef3b in gst_element_post_message (element=0xfd22f0, message=0xc25580)
    at gstelement.c:1853
#4  0x00007ffff3869bc7 in gst_bin_handle_message_func (bin=0xfd22f0, message=0xc25580)
    at gstbin.c:3442
#5  0x00007ffff389ee88 in gst_pipeline_handle_message (bin=0xfd22f0, message=0xc25580)
    at gstpipeline.c:587
#6  0x00007ffff3867558 in bin_bus_handler (bus=<optimized out>, message=<optimized out>,
    bin=<optimized out>) at gstbin.c:2793
#7  0x00007ffff3870fac in gst_bus_post (bus=0xd133c0, message=0xc25580) at gstbus.c:322
#8  0x00007ffff387ef3b in gst_element_post_message (element=0xfcc360, message=0xc25580)
    at gstelement.c:1853
#9  0x00007ffff3893453 in do_stream_status (pad=0xfcf360, type=GST_STREAM_STATUS_TYPE_ENTER, task=
    0xfd44c0, thread=<optimized out>) at gstpad.c:5544
#10 0x00007ffff38c1cb0 in gst_task_func (task=0xfd44c0) at gsttask.c:294
#11 0x00007ffff5b2d248 in g_thread_pool_thread_proxy (data=<optimized out>)
    at /build/buildd/glib2.0-2.32.3/./glib/gthreadpool.c:309
#12 0x00007ffff5b2c9e5 in g_thread_proxy (data=0xb32230)
    at /build/buildd/glib2.0-2.32.3/./glib/gthread.c:801
#13 0x00007ffff7bc4e9a in start_thread (arg=0x7ffff2794700) at pthread_create.c:308
#14 0x00007ffff69b64bd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#15 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7ffff7fdd700 (LWP 10408)):
#0  sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:86
#1  0x00000000005294df in PyEval_RestoreThread ()
#2  0x000000000052a0d2 in PyGILState_Ensure ()
#3  0x00007ffff43f5c61 in bus_sync_handler (bus=0xd13480, message=0x7fffec003a80,
    user_data=0x9cad40) at gstbus.override:44
#4  0x00007ffff3870fac in gst_bus_post (bus=0xd13480, message=0x7fffec003a80) at gstbus.c:322
#5  0x00007ffff387ef3b in gst_element_post_message (element=0xfd22f0, message=0x7fffec003a80)
    at gstelement.c:1853
#6  0x00007ffff3869bc7 in gst_bin_handle_message_func (bin=0xfd22f0, message=0x7fffec003a80)
    at gstbin.c:3442
#7  0x00007ffff389ee88 in gst_pipeline_handle_message (bin=0xfd22f0, message=0x7fffec003a80)
    at gstpipeline.c:587
#8  0x00007ffff3867558 in bin_bus_handler (bus=<optimized out>, message=<optimized out>,
    bin=<optimized out>) at gstbin.c:2793
#9  0x00007ffff3870fac in gst_bus_post (bus=0xd133c0, message=0x7fffec003a80) at gstbus.c:322
#10 0x00007ffff387ef3b in gst_element_post_message (element=0xfd6500, message=0x7fffec003a80)
    at gstelement.c:1853
#11 0x00007ffff3b4001a in gst_base_sink_change_state (element=0xfd6500,
    transition=GST_STATE_CHANGE_PAUSED_TO_READY) at gstbasesink.c:5170
#12 0x00007ffff387fdac in gst_element_change_state (element=0xfd6500, transition=<optimized out>)
    at gstelement.c:2761
#13 0x00007ffff38806d0 in gst_element_set_state_func (element=0xfd6500, state=GST_STATE_READY)
    at gstelement.c:2717
#14 0x00007ffff386d8ed in gst_bin_element_set_state (next=GST_STATE_READY,
    current=GST_STATE_PAUSED, start_time=0, base_time=0, element=0xfd6500, bin=0xfd22f0)
    at gstbin.c:2209
---Type <return> to continue, or q <return> to quit---
#15 gst_bin_change_state_func (element=0xfd22f0, transition=GST_STATE_CHANGE_PAUSED_TO_READY)
    at gstbin.c:2518
#16 0x00007ffff389f2e4 in gst_pipeline_change_state (element=0xfd22f0,
    transition=GST_STATE_CHANGE_PAUSED_TO_READY) at gstpipeline.c:482
#17 0x00007ffff387fdac in gst_element_change_state (element=0xfd22f0, transition=<optimized out>)
    at gstelement.c:2761
#18 0x00007ffff38806d0 in gst_element_set_state_func (element=0xfd22f0, state=GST_STATE_NULL)
    at gstelement.c:2717
#19 0x00007ffff43fa52d in _wrap_gst_element_set_state (self=0xf2e7d0, args=<optimized out>,
    kwargs=<optimized out>) at gstelement.override:71
#20 0x000000000042a485 in PyEval_EvalFrameEx ()
#21 0x00000000004317f2 in PyEval_EvalCodeEx ()
#22 0x000000000054b171 in PyRun_FileExFlags ()
#23 0x000000000054b7d8 in PyRun_SimpleFileExFlags ()
#24 0x000000000054c5d6 in Py_Main ()
#25 0x00007ffff68e576d in __libc_start_main (main=0x41b900 <main>, argc=2, ubp_av=0x7fffffffe2a8,
    init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=
    0x7fffffffe298) at libc-start.c:226
#26 0x000000000041b931 in _start ()